Vertical moving horizontal aperture ring positron emission tomography scanner and chair with stationary cycle for stressing the patient&#39;s heart

ABSTRACT

A positron emission tomography (PET) scanner in which a horizontal detector ring is arranged to be moved vertically up and down by a lifting mechanism, thereby eliminating the need for a patient to be in a supine position when performing PET or other types of image scanning.

BACKGROUND OF THE INVENTION 1. Field of the Invention

The present invention generally relates to medical imaging systems. Moreparticularly, the present invention relates to a vertical-movinghorizontal ring PET scanner.

2. Description of the Prior Art

Medical imaging technology has made remarkable advances over the yearsincluding developments and improvements on positron emission tomography(PET). The use of PET has grown in the field of medical imaging. PET hasgained attention as being effective in making an early diagnosis ofcancers, heart diseases, cerebrovascular disorders, dementia and others.PET is an imaging method that relies on injecting IV, a compound labeledwith a trace amount of a positron emitting nuclide. The PET's detectorring identify paired photons (511 keV of energy each) produced by thepositron annihilation effect. The paired 511 keV photons travel in theopposite direction at a 180° angle from each other. Therefore, positrondecay can be localized without collimation, as used for SPECT, but withthe use of the principle of coincidence detection. As PET cameras do notnecessitate collimators, these systems have a much higher sensitivitythan do SPECT cameras. PET scan is a map of radioactive concentration invarious tissues based on the specific biochemical properties of thetracer. For example, metabolism of glucose or blood flow in heart muscle(myocardium), and examining the presence or absence of a disease and theseriousness of a disease, and prognoses during the course of therapy.For the implementation thereof, PET scanners have been put intopractical use. Another advantage of PET vs. SPECT is its capability tomeasure the radioactive concentration inside the body without thedisturbing effect of tissue attenuation.

PET-myocardial perfusion imaging (MPI) allows accurate measurement ofmyocardial perfusion, absolute myocardial blood flow and function atstress and rest in a single study session performed in approximately 30minutes. Various PET tracers are available for MPI and rubidium-82 ornitrogen-13-ammonia is most commonly used. Relative quantification ofPET perfusion images shows very high diagnostic accuracy for detectionof obstructive coronary artery disease. Dynamic myocardial blood flowanalysis has demonstrated additional prognostic value beyond relativeperfusion imaging.

A PET Myocardial Perfusion Imaging (MPI) Stress Test consists ofintravenous injection of Ru-82 or N-13 labeled ammonia while the heartis at rest. These isotopes have relatively short half-lives (76 secondsand 9.8 minutes respectively). After a few minutes of imaging the heartat rest, the patient is asked to exercise on a treadmill or a stationarycycle. When the heart reaches its peak stress, a second IV injection ofthe radioactive tracer and a second set of “stress” images are collectedby the PET scanner. If a region of the myocardium shows relative loweruptake of radioactivity in the resting image, it may indicate infarct inthe myocardium. If the resting image is uniform, but a defect is shownin the “stress” image, it is a sign of ischemia in that region.

Ischemic heart disease (IHD) remains a major healthcare issue in theUnited States, and often results in myocardial infarction (MI) andadverse post-MI left ventricle (LV) remodeling, which manifests aschanges in LV structure, volume, geometry, and function. An estimatedeight million people are afflicted with MI in the United States witharound 610,000 new cases reported each year.

Significant progress has been made in the development of dynamicpositron emission tomography (PET) perfusion imaging to accuratelyquantify coronary flow reserve, CFR as the ratio of absolute globalmyocardial blood flow (MBF) measured at peak stress (i.e. duringvasodilator induced hyperemia) over that at rest (which is corrected forrate-pressure product as an index of baseline cardiac work). From apathophysiologic perspective, CFR provides a measure of the integratedeffects of epicardial coronary artery disease CAD, diffuseatherosclerosis, vessel remodeling, and microvascular dysfunction onmyocardial tissue perfusion.

In contrast to SPECT, PET offers the possibility to routinely quantifyperfusion in absolute terms and calculate coronary flow reserve (CFR),which has incremental prognostic value over evaluation of perfusiondefects alone. It is demonstrated that a blunted CFR was one of thestrongest prognostic factors and trumps clinical risk scores as well asrelative perfusion abnormalities.

Conventionally, a cylindrical geometry is the design of choice for a PETscanner. As shown in FIG. 1, the cylindrical geometry can capture allevents in the transaxial plane. The axial extent of the detector willdetermine how many such planes can be defined, as well as how manyoblique planes can be utilized.

SUMMARY OF THE INVENTION

A PET scanner is a large scanning machine with a usually round, doughnutshaped hole in the middle, similar to a computed tomography (CT) ormagnetic resonance imaging (MRI) unit. Within this PET scanner aremultiple detectors that record the annihilation photons emitted from theradiotracer in a patient's body. The present invention relates to anindependent vertical-moving horizontal PET detector ring therebyenabling scanning a patient in seated or standing position, andconsequently decreasing the footprint of the whole system. This seatingposition has distinct advantages, particularly in scanning the heartthat will be described below.

In order to measure the value of coronary flow reserve (CFR) the PETimaging should starts immediately after the heart reaches its peakstress level. This is not possible if treadmill is used to stress thepatient because it takes time for the patient to walk to the PET scannerand be positioned for imaging.

With the present invention of a vertical PET scanner and a stationarycycle for “stressing” the patient while positioned inside the PETdetector ring, scanning can start immediately after the heart reachesits peak stress. This allows quantification of myocardial blood flow, aswell as the myocardial flow reserve that is important for diagnosis ofmicrovascular disease, a very important issue especially for women.

Further novel features and other objects of the present invention willbecome apparent from the following detailed description, discussion andthe appended claims, taken in conjunction with the drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

Referring particularly to the drawings for the purpose of illustrationonly and not limitation, there is illustrated:

FIG. 1 is a perspective view of a prior art positron emission tomography(PET) scanner with a gantry table;

FIG. 2 is a perspective view of the present invention vertical-movingPET scanner with a horizontal aperture detector ring;

FIG. 3a illustrates the present invention vertical-moving PET scannerwith the horizontal aperture detector ring at its highest verticalposition for a patient in a wheelchair to be rolled into position forscanning;

FIG. 3b illustrates the present invention vertical-moving PET scannerwith the horizontal aperture detector ring being lowered into positionfor imaging while the patient is sitting in the wheelchair;

FIG. 3c illustrates the present invention vertical-moving PET scannerwith the horizontal aperture detector ring in a lower cardiac scanningposition while the patient is in the wheelchair;

FIG. 4a illustrates the present invention vertical-moving PET scannerwith the horizontal aperture detector ring in a lower chest scanningposition to scan the breast area of the patient sitting in thewheelchair;

FIG. 4b illustrates the present invention vertical-moving PET scannerwith the horizontal aperture detector ring in a raised position to allowa doctor to perform a biopsy on the patient, or other types of imaging(e.g. ultrasound or x-ray mammogram) while sitting in the wheelchair;

FIGS. 5a and 5b illustrate an alternative embodiment of the presentinvention PET scanner with a horizontal aperture detector ring situatedon a platform, where a patient is sitting in a wheelchair and rolledinto a vertical lift to be raised or lowered into position for scanning;

FIG. 6a is a cross sectional view of the present inventionvertical-moving PET scanner with the horizontal aperture scan ring atits lowest position, showing the basic construction elements and takenalong lines 6 a-6 a of FIG. 2;

FIG. 6b is a cross sectional view of the present inventionvertical-moving PET scanner with the horizontal aperture detector ringat its highest vertical position, showing the basic constructionelements;

FIG. 7a illustrates a specialized wheelchair for cardiac imaging in atransport position to be used in conjunction with the present inventionvertical-moving PET scanner with a horizontal aperture scan ring shownin FIG. 2;

FIG. 7b illustrates the specialized wheelchair shown in FIG. 7a in anexercise position to be used in conjunction with the present inventionvertical-moving PET scanner with a horizontal aperture scan ring shownin FIG. 2; and

FIG. 7c illustrates the specialized wheelchair shown in FIG. 7a in ascanning position to be used in conjunction with the present inventionvertical-moving PET scanner shown in FIG. 2.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Although specific embodiments of the present invention will now bedescribed with reference to the drawings, it should be understood thatsuch embodiments are by way of example only and merely illustrative ofbut a small number of the many possible specific embodiments which canrepresent applications of the principles of the present invention.Various changes and modifications obvious to one skilled in the art towhich the present invention pertains are deemed to be within the spirit,scope and contemplation of the present invention as further defined inthe appended claims.

Described briefly, the present invention relates to a vertically-movinghorizontal aperture body scanner, so that it's 360° detector ring can bepositioned and re-positioned. At the highest position of the detectorring provides an unobstructed path for patient insertion and removal.The detector ring has multiple downward positions which permit sectionsof 360° scans with multiple slices. Scans could also be sequenced fromthe bottom position upwards. Vertically seated or standing patients canbenefit from analysis of heart and other scanned areas of the bodysubjected to stress by exercise during, or immediately before scans. Themass of the detector ring and its sensitive sensors and electronics issecured for stable vertical movement by distributed lift mechanisms.There is the added option wherein a patient could be scanned, aprocedure performed such as a biopsy, and then scanned to verify theprocedure. Other modalities of medical imaging can be performed and theresulting imaging fused to the PET images. Vertical positioning scanningis more compact for a seated or standing patient. Scanning time savingsis accomplished by using a specialized wheelchair, because positioningof the patient is done outside the PET scanner and even the initial partof the exercising can happen while another patient is being scanned. Byhaving multiple specialized wheelchairs available, a higher throughputcan be achieved in a medical imaging center.

Referring to FIG. 1, there is shown a prior art positron emissiontomography (PET) scanner 2 which comprises a vertical ring detector 4, agantry table 6, and a computer system (not shown). A support on thegantry table 6 is horizontally moved into the bore 5 of the detectorring 4 in response to commands received from the computer system. Thecomputer system typically includes a display and one or more inputdevices such as a keyboard or a mouse. Through the keyboard andassociated input devices, the operator can control the operation of thePET scanner 2 and the display of the resulting images on the display.

Referring to FIG. 2, there is shown the present inventionvertical-moving PET scanner 10 which includes a horizontal aperture scandetector ring 12 and two opposite support lifting structures 14 and 16.The scan detector ring 12 has a horizontal aperture 18 which isconfigured and situated substantially parallel to the floor. The PETscanner 10 is well known and conventional in the art, and thedescription will not be described in details but will only be describedin general terms as the PET scanner 10. The mass of the scan detectorring 12 and its sensitive sensors and electronics is secured for stablevertical movement by distributed support lifting structures 14 and 16.

Referring to FIG. 3a , there is shown the vertical-moving PET scanner 10with the horizontal aperture 18 detector ring 12 at its highest verticalposition for a patient 8 sitting in a specialized wheelchair 110 to berolled into position for image scanning.

Referring to FIG. 3b , there is shown the vertical-moving PET scanner 10with the horizontal aperture 18 detector ring 12 being lower while thepatient 8 is sitting in the wheelchair 110 to be scanned.

Referring to FIG. 3c , there is shown the vertical-moving PET scanner 10with the horizontal aperture 18 detector ring 12 in a lower cardiac scanposition while the patient 8 is sitting in the wheelchair 110 to bescan.

Referring to FIG. 4a , there is shown the vertical-moving PET scanner 10with the horizontal aperture 18 detector ring 12 in a lower chestscanning position to scan the breast area of the patient 9 sitting inthe wheelchair 110.

Referring to FIG. 4b , there is shown the vertical-moving PET scanner 10with the horizontal aperture 18 detector ring 12 in a raised position toallow a doctor to perform a biopsy, deliver local therapy guided by thePET image, or other imaging procedures on the patient 9 sitting in thewheelchair 110.

Referring to FIG. 5a , there is shown an alternative embodiment of thevertical-moving PET scanner 10 situated on a platform 20, where apatient 9 is sitting in a wheelchair 110 and rolled into a middlevertical lift 22 and raised into position for PET scanning.

Referring to FIG. 5b , there is shown the alternative embodiment of thevertical-moving PET scanner 10 situated on the platform 20, where thepatient 9 is sitting in the wheelchair 110 and rolled into the middlevertical lift 22 for PET scanning.

Referring to FIG. 6a , there is shown a cross sectional view taken alonglines 6 a-6 a of the present invention vertical-moving PET scanner 10with the horizontal aperture detector ring 12 at its lowest position,showing the basic construction elements.

Referring to FIG. 6b , there is shows a cross sectional view of thepresent invention vertical-moving PET scanner 10 with the horizontalaperture scan ring 12 at its highest vertical position, showing thebasic construction elements. Each of the support lifting structures 14and 16 includes 2 opposite lifting columns 24 which are identical. Eachlifting column 24 can be raised or lowered by electrical motor orhydraulic system known in the art. These 4 lifting columns 24 areutilized to distribute the weight of the horizontal aperture detectorring 12 to be raised or lowered by the computer system.

Referring to FIG. 7a , there is shown a specialized wheelchair 110 in atransport position to be used in conjunction with the present inventionvertical-moving PET scanner 10 with a horizontal aperture detector ring12 shown in FIG. 2.

The wheelchair 110 includes a pivot handlebar portion 112, a seatportion 116, a leg portion 114, and an arm portion 118. The handlebarportion 112 and the leg portion 114 are shown in its transport position.

Referring to FIG. 7b , there is shown the specialized wheelchair 110 inits exercise position to be used in conjunction with the presentinvention vertical-moving PET scanner 10 shown in FIG. 2.

In the exercise position, the leg portion 114 is extended as shown toallow the patient sitting in the wheelchair 110 to exercise.

Referring to FIG. 7c , there is shown the specialized wheelchair 110 inits scanning position to be used in conjunction with the presentinvention vertical-moving PET scanner 10 shown in FIG. 2.

In the scanning position, the leg portion 114 is positioned downwardlyand both the handlebar portion 112 and the arm portion 118 are pivoteddown to allow the patient sitting in the seat portion 116 to be scannedtogether without any issue.

The configuration or placement of the horizontal aperture detector ring18 can be utilized with other imaging devices, such a computedtomography (CT) unit or a magnetic resonance imaging (MRI) unit or etc.

The present invention can also be a method of scanning a patient's bodyvertically seated or standing and can benefit from analysis of heart andother scanned areas of the body subjected to stress by exercise during,or immediately before scans.

Of course the present invention is not intended to be restricted to anyparticular form or arrangement, or any specific embodiment, or anyspecific use, disclosed herein, since the same may be modified invarious particulars or relations without departing from the spirit orscope of the claimed invention hereinabove shown and described of whichthe apparatus or method shown is intended only for illustration anddisclosure of an operative embodiment and not to show all of the variousforms or modifications in which this invention might be embodied oroperated.

The present invention has been described in considerable detail in orderto comply with the patent laws by providing full public disclosure of atleast one of its forms. However, such detailed description is notintended in any way to limit the broad features or principles of thepresent invention, or the scope of the patent to be granted. Therefore,the invention is to be limited only by the scope of the appended claims.

What is claimed is:
 1. A method for vertically imaging a region ofinterest of a patient while the patient is sitting or standing within aPET scanning area, the method comprising the steps of: providing ahorizontal PET scan detector ring having a horizontal aperture, thedetector ring having a detector depth of at least six inches and adiameter of at least sixty inches for fully imaging a cross section ofsignificant organ areas of said patient; attaching at least threevertical ring columns equally spaced apart from each other at an outersurface of said scan detector ring for providing support and tostabilized image acquisition over the minutes required for scan detectorring; providing transport means to transport said patient to said PETscanning area, the transport means having a seat portion, a handlebarportion, an arm portion, and a leg portion where the handlebar portionand the arm portion are pivotable downward to allow the patient sittingin the seat portion to be scanned while in the transport means;attaching at least three synchronized motorized devices eachrespectively to said at least three vertical ring columns for verticallyraising said scan detector ring to allow said transport means to entersaid PET scanning area in a vertical position and lowering saidhorizontal aperture of said scan detector ring to scan said region ofinterest of said patient while said patient is sitting or standing insaid transport means and providing vertical precise repeatabilityimaging so that multiple cross sections are aligned within a software;and controlling said horizontal aperture of said scan detector ring toscan said patient vertical cross sections which are horizontally flatwith repeatable horizontal image planes so that multiple cross sectionsare aligned while said patient is sitting or standing within saidscanning area of said detector ring.
 2. The method in accordance withclaim 1 wherein said at least three synchronized motorized devices areelectrical motors.
 3. The method in accordance with claim 1 wherein saidat least three synchronized motorized devices are hydraulic.
 4. Themethod in accordance with claim 1 wherein said seat portion is made outof scannable material.
 5. The method in accordance with claim 1 whereinsaid controlling said horizontal aperture of said scan detector ringincludes a computer system.
 6. A PET imaging scanner for verticallyimaging a region of interest of a patient within a scanning area, thePET imaging scanner comprising: a horizontal scan detector ring having ahorizontal aperture, the detector ring having a detector depth of atleast six inches and a diameter of at least sixty inches for fullyimaging a cross section of significant organ areas of said patient; atleast three vertical ring columns equally spaced apart from each otherand attached to an outer surface of said scan detector ring forproviding support and to stabilized image acquisition over the minutesrequired for said PET imaging scanner; at least three synchronizedmotorized devices each respectively attached to said at least threevertical ring columns for providing vertical precise repeatabilityimaging so that multiple cross sections are aligned within a software;and a computer system for controlling a vertical scanning of said organareas of said patient within said horizontal aperture of said scandetector ring while said patient is sitting or standing within saidhorizontal aperture.
 7. The PET imaging scanner in accordance with claim6 wherein said at least three synchronized motorized devices includeselectrical motors.
 8. The PET imaging scanner in accordance with claim 6wherein said at least three synchronized motorized devices includeshydraulic.
 9. A PET imaging scanner for vertically imaging a region ofinterest of a patient within a scanning area, the PET imaging scannercomprising: a horizontal scan detector ring having a horizontalaperture, the detector ring having a detector depth of at least sixinches and a diameter of at least sixty inches for fully imaging a crosssection of significant organ areas of said patient; four vertical ringcolumns equally spaced apart from each other and attached to an outersurface of said scan detector ring for providing support and tostabilized image acquisition over the minutes required for said PETimaging scanner; four synchronized motorized devices each respectivelyattached to said four vertical ring columns for providing verticalprecise repeatability imaging so that multiple cross sections arealigned within a software; and a computer system for controlling avertical scanning of said organ areas of said patient within saidhorizontal aperture of said scan detector ring while said patient issitting or standing within said horizontal aperture.
 10. The PET imagingscanner in accordance with claim 9 wherein said four synchronizedmotorized devices includes electrical motors.
 11. The PET imagingscanner in accordance with claim 9 wherein said four synchronizedmotorized devices includes hydraulic.